The number and frequency of patient operations throughout the world has increased notably over the past 25 years. Today there are approximately 25 million post-operative patients a year in the U.S. alone. Assuming the average post-operative patient remains in the hospital 2½ days, this correlates to approximately 62.5 million post-op days and a demand of approximately 180,000 independent devices for controlling and monitoring narcotic delivery. Thus, there is an increasing and wide-spread demand for devices, methods, and systems for monitoring and controlling the status of post-operative patients and the effects of narcotics upon the same. In addition, sleep apnea is increasingly being diagnosed, and this expanding patient group is more sensitive to narcotics, creating additional risks and demand for timely treatment of endangered breathing.
A common narcotic delivery device used in patients, usually post-operative patients, is known as the patient-controlled analgesia pump (“PCA pump”). A PCA pump permits the patient to control the dosage of narcotic (typically in response to increased pain) by pressing a button that activates the pump and delivers a certain amount of narcotic. PCA pumps from several manufacturers have been recalled by the FDA because of malfunction, tampering and unknown errors, permitting unsafe doses of narcotics to be delivered in a certain period of time. In efforts to prevent further harm to patients, various companies, agencies, etc. have focused on trying to improve the efficacy of PCA pumps, in an effort to eliminate the possibility of overdose, user error and/or intentional tampering. Despite these efforts, PCA pumps and associated user error have been implicated in deaths from overdose, even in young (ages 21-35 years of age), healthy patients. Despite these efforts, it has become clear that user error and unpredictable patient factors still result in fatal errors and serious complications, and that current narcotic delivery systems still carry a significant risk of patient harm in connection with PCA pumps.
It is also known that post-operative patients and other vulnerable patients, whether or not treated with narcotics, may be at risk for suffering from respiratory-related problems including respiratory depression and sleep apnea. Most PCA pumps and other automated bedside patient monitoring equipment do not supply adequate control or signaling to address these types of problems. For optimal patient care, better monitoring of patients should be mandatory for the timeliest detection of life-threatening respiratory events occurring in post-operative and other vulnerable patients.
Despite whether an automated delivery device (PCA) is employed or not, overdose is a significant risk in all patients. The Anesthesia Patient Safety Foundation, the Institute for Safe Medical Practices, the American College of Surgeons and the Joint Commission of Accreditation for Hospitals have determined that patients given narcotics after surgery are being inadequately monitored and are at risk. Furthermore, hospitalized patients are generally at higher risk for various complications regardless of exposure to narcotics. In a narcotic overdose situation caused by a pump delivery system or human error, optimal monitoring helps care-givers discover a crisis earlier than currently possible, which minimizes critical time-to-treatment. Suboptimal monitoring of differing patient types may result in life-threatening outcomes in post-operative patients given narcotics for pain control. In addition, respiratory depression can lead to stroke, heart attack, brain injury, and death, even in young, healthy patients. If a patient stops breathing, hospital staff or other care providers would prefer to detect it immediately, and common monitoring systems are generally too slow or unresponsive to provide the information necessary to timely respond to respiratory depression (without oxygen, brain death occurs in about three minutes).
To complicate this problem further, most patients are not monitored continuously, but rather simply have a nurse periodically visiting a patient's room to count their respirations. Generally, only patients in an operating room are monitored on a continuous basis with an expert in airway management present (Anesthesiologist). Thus, given these conditions, it is impossible for staff or other care providers to sufficiently monitor patients to prevent disasters outside the operating room. In post-operative and many other patient-care situations, there are substantial risks that complications will arise that require attention within seconds, but, appropriate care and intervention is usually minutes away.
Abnormal breathing and monitoring thereof may provide a valuable indication that serious events are about to occur, have just occurred, or are occurring. Timely warnings can assist in responding to and treating these events as soon as possible to minimize risk of disability or death. Superior monitoring of patients results in better outcomes due to earlier detection of respiratory or breathing-related problems.
Outside of operating rooms, the most commonly used breathing monitor besides occasional visits by staff to count respirations is “pulse oximetry,” which has been in existence for over 20 years and has greatly improved the safety of patients. The pulse oximetry apparatus generally consists of a clip-on monitor (typically on a finger or on an earlobe) that detects the amount of oxygen in a patient's blood stream. Unfortunately, when a patient stops breathing, it might take minutes for the oxygen level in their blood stream to drop to a dangerously low level that will be detected with pulse oximetry. Therefore, pulse oximetry is relatively insensitive and slow in detecting a breathing crisis and leaves less time to correct that problem before irreversible damage begins to occur.
Recently, an acoustic monitor (measuring the sound of breathing) has been used with success in patients to detect air movement in and out of the lungs. It may be an alternative to pulse oximetry in the early detection of cessation or slowing of breathing. However, current technology is limited by ambient noise and not recommended for patients less than twelve years old or larger patients with increased adipose tissue.
End-tidal CO2 monitors (capnography) provide the most sensitive means (100% sensitive) for providing the earliest detection of respiratory depression from narcotic overdose and disasters that might follow. “End-tidal” carbon dioxide refers to the amount of carbon dioxide exhaled at the end of a breathing cycle. An end-tidal monitor operates on the principle that if sufficient carbon dioxide is not being exhaled, sufficient oxygen is similarly not being inhaled—an obviously life-threatening situation that requires adequate monitoring for hospital and post-hospital settings. These types of CO2 monitors have been used for anesthesia monitoring during surgery and increasingly for intensive care monitoring, emergency departments and in ambulances.